The code from ks8851.c was moved to ks8851_common.c, so it was not
backported. This broke the compile of the omap target which uses this
driver.
Fixes commit 91a52f22a1 ("treewide: backport support for nvmem on non platform devices")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>